I've been getting nagged a bit to finally get around to installing an electrical noise filter I acquired 6 or 8 months back for use in a 2005 vintage FB70. When the boiler kicks on it causes horrendous static and interference on any radio in the facility - despite it being across the room and on a different circuit.

Now that I'm ready to do the install I pulled out the "instructions" that Franke Coffee sent along with the part. That page consists only of an enlargement of one corner of the wiring schematic for the machine. Everyone I talked to at the time seemed clueless about where to install the part. The schematic shows the L1 and L3 heating element connections going to A1 and A2 on the pressure switch. That in turn connects via T1 and T3 to what I assume is the On/Off switch (it's not in the drawing but if I look at the full schematic in my manual that's where they go).

The terminals for the pump motor connector appear in this drawing as do the connections to the two thermal limit switches.

It's the contactor that causes the interference. This filter goes on the contactor A1 and A2 contacts. It's classic Marzocco, the power for the A1 + A2 are flat spade crimp terminals and the filter uses bootlace straight ferrules so when you tighten the screw the washer is at an angle.

I think earlier machines used Allen Bradley switches which are very noisy, the Telemecanique TeSys switches are quieter.

Easy easy easy. Took almost as long to pull the cups off the top of the machine and replace them later as it did to install the filter. And it works like a charm. Static free radio - what a concept.

The plastic casing of the pressure switch was a a bit brittle and conveniently enough... when I was probing with a fine tipped screwdriver to see where to squeeze the rounded tips of the filter in the edges adjacent to the A1 and A2 terminals popped off and provided a good visual reference.

BY removing the top of the machine you can pull out the switch and there\'s just enough play on the wires to get it turned at an angle and get a screwdriver in to loosen the screws that hold the spade lugs tight in A1 and A2. Best tool would be a stubby handled Philips head with a narrow diameter shaft and a standard size tip but I made do with one that had a longer shaft. The shaft diameter of my stubby was a bit too wide to fit into the hole that comes in up underneath A1 and A2 to all access to the screws.

The part itself

Pressure switch as seen from the customer side of the machine

Round wire ends of noise filter slip in under lugs. I put them in on the sides because I bolloxed the edges of the switch and they snapped off on the corners but with more finesse and a fully loosened screw they should easily fit in by running them on on top of the wire lug and parallel to it.

Fully attached wire ends of filter before repositioning the switch back under the metal enclosure that it clips into.

Completed installation with filter tucked up on top of wires and out of the way.

Update: The A1 and A2 terminals really aren't designed to take anything other than the spade lug from the appropriate connecting wires. despite my best efforts - one side seems to be staying firmly connected and the other side keeps slipping loose. When that occurs it isn't just the noise filter coming undone - the entire spade lug slips out and we have no steam power until it's reconnected.

This happened again recently while I was out of town. The shop owner got it back in there for now but I'm planning to strip back the sheathing behind the spade lugs on each wire... solder the ends of the noise filter wires onto the bare wire... slide some shrink wrap tubing over each one and be done with it.